Recipe Tips

Preparation

Cook beans in large pot of boiling salted water until crisp-tender, about 4 minutes. Drain. Transfer beans to large bowl of ice water to cool. Drain; pat dry. Whisk vinegar, mustard and parsley in small bowl to blend. Gradually whisk in oil. Season with salt and pepper. DO AHEAD Can be made 1 day ahead. Cover beans and vinaigrette separately; chill. Rewhisk before using. Combine beans, watercress, walnuts and tomatoes in large bowl. Toss with enough vinaigrette to coat. Season to taste with salt and pepper.